This invention relates to a relatively flat flexible electrical heating panel and methods of fabricating such panels.
The prior art contains a plethora of patents which relate to electrical heating panels which essentially incorporate flexible resistive elements mounted on suitable backings. Such panels have widespread use as in blankets, heating pads, hot plates, or in any application where heat is desired by the use of a relatively thin and compact configuration. The panels function to provide heat by the application of a suitable current to the panel. The resistors which usually form a flat array produce heat due to the power dissipated in the resistive array when subjected to an electrical current.
As can be ascertained, there is a need to fabricate and produce such a panel in any desired size as economically and efficiently as possible. The panels should also provide a sufficient amount of heat without producing smoke or odor when they are subjected to an operating current. These properties are desirable as should be apparent. Many prior art panels incorporate bonding elements and resistive elements which undesirably produce odors and smoke during operation. These objectional characteristics are provided, even though the panel may be operating satisfactorily. Hence, as one can ascertain, the generation of both or either of the above noted conditions will result in many consumer and customer complaints in using and employing the panel.
As indicated above, many uses and various structures have such panels and are known in the prior art and many patents exist which show particular types of configurations and formats.
Patents such as U.S. Pat. No. 3,774,299 entitled "Method for Production of Panel Heater" issued on Nov. 27, 1973 describes a technique of producing a panel heater employing the steps of mixing a carbon fiber with natural or synthetic fibers. The mixture is formed on a sheet of base material and the sheet is then heated to expel volatile matter. Essentially, the panel is of a composite configuration which is typical of many prior art panels.
U.S. Pat. No. 3,417,229 issued on Dec. 17, 1968 shows a flexible panel employing resistive strips as heating elements. The strips are encapsulated within a flame retardant flexible material.
Other patents such as U.S. Pat. Nos. 3,423,574, 3,546,432, 3,591,753, 3,721,250, 3,749,886, 3,766,644, 3,813,520, 3,814,898, 3,875,373, 3,909,591, 3,987,717, 4,016,654, 4,034,206, 4,052,588 and many other patents too numerous to cite, show various alternate constructions of flexible heating panels and particularly depict numerous and various applications in which such panels are directed for use.
Accordingly, it is a primary object of the present invention to provide a panel which provides smokeless and odorless operation and based on its construction and fabrication enables utilization in a variety of widespread and diverse applications. The particular panel and the techniques for producing the same assure reliable operation, while avoiding many of the difficulties inherent in the prior art devices.